Recently, development of hydrogen production apparatuses that produce hydrogen on location (on site) has been conducted using natural gas, city gas, or the like as a source gas. Such a hydrogen production apparatus is used in industrial applications such as bright annealing of metals such as steel plates or glass manufacturing, and also is installed on the island of Chubu International Airport, for example, as a hydrogen station that replenishes hydrogen in fuel cell vehicles.
As an example of this sort of hydrogen production apparatus, an apparatus is known that is provided with a desulfurizer that desulfurizes a source gas that is pressure-fed by a pressure feeding apparatus, a reformer that heats the desulfurized source gas in a state mixed with steam and obtains a reformed gas, a CO transformer that causes carbon monoxide in the reformed gas from the reformer to react with steam to obtain a hydrogen-rich gas, and a hydrogen purification unit (for example, an apparatus using a PSA scheme) that separates impurities other than hydrogen from the hydrogen-rich gas to purify the hydrogen.
When producing hydrogen in the hydrogen purification apparatus, it is necessary to maintain the desulfurizer at about 200 to 300° C., the reformer at about 700 to 800° C., and the CO transformer at about 200 to 450° C., and therefore, for example, a configuration is adopted in which a heating apparatus is provided that burns a fuel gas (for example, a city gas 13A) supplied from the outside to increase the temperature of a catalyst of the reformer, and by guiding the reformed gas at a relatively high temperature, which has been heated by passing through the heated reformer catalyst, to the CO transformer, the temperature of the CO transformer is increased, and also, the temperature of the desulfurizer provided in the CO transformer is increased as well.
Also, as another hydrogen production apparatus, an apparatus is known that is provided with a reformer that mixes steam with a source gas and heats the mixture to obtain a reformed gas, a pressure increasing apparatus that increases the pressure of the reformed gas, and a PSA-type hydrogen purification unit that separates the reformed gas at increased pressure into hydrogen and off-gas other than hydrogen (see Patent Document 1).
In the hydrogen production apparatus disclosed in Patent Document 1, a closed circulation circuit is formed where gas is circulated between the desulfurizer, the reformer, and the CO transformer. Gas is circulated in the closed circulation circuit during a start-up operation, and after the temperature of the gas is increased, a hydrogen purification operation by the hydrogen purification unit is started. Thus, loss of time when starting up the hydrogen purification unit is reduced.